Present Senior Staff

CIC

Admiral William Adama - Commanding Officer
Colonel Saul Tigh - Executive Officer
Lieutenant Felix Gaeta - Tactical officer, Senior Officer of the Watch
Lieutenant Hoshi - Communications Officer
Lieutenant Anastasia Dualla

Air Wing

Major Lee Adama
Captain Karl Agathon - Acting CAG
Lieutenant Sharon Agathon

Support

Major Cottle - Chief Medical Officer
Captain Aaron Kelly - Landing Signal Officer, Second Officer
Chief Petty Officer Galen Tyrol - Chief of the Deck
Gunnery Sergeant Erin Mathias - Senior Marine NCO

Position Histories

Commanding Officer

Commander William Adama (Miniseries to "Scattered") - Injured after assassination attempt
Colonel Saul Tigh, Acting ("Scattered" to "The Farm") - Relinquishes command after Commander Adama returns to duty
Admiral William Adama ("The Farm" to present) - Promoted to Admiral by President Roslin ("Resurrection Ship, Part II")

Executive Officer

Colonel Saul Tigh (Miniseries to "Scattered") - Assumes command when Commander Adama is injured during an assassination attempt
Captain Aaron Kelly ("Scattered" to "The Farm") - Returns to regular duties when Commander Adama resumes command
Colonel Saul Tigh ("The Farm" to "Lay Down Your Burdens, Part II") - Relocates to New Caprica
Captain Karl Agathon ("Occupation" to "Unfinished Business") - Demoted when Colonel Tigh resumes post
Colonel Saul Tigh ("The Passage" to present)

Tactical officer

Lieutenant Felix Gaeta (Miniseries to "Lay Down Your Burdens, Part II") - Relocates to New Caprica
Captain Karl Agathon ("Lay Down Your Burdens, Part II") - Promoted to XO
Captain Aaron Kelly ("Occupation" to "The Passage") - Gaeta resumes post
Lieutenant Felix Gaeta ("The Passage" to present)

Communications Officer

Petty Officer 2nd Class Anastasia Dualla (Miniseries to "Lay Down Your Burdens, Part II") - Promoted to XO of Pegasus
Unknown ("Occupation" to "Exodus, Part II")
Lieutenant Hoshi ("Collaborators" to present)

Commander, Air Group

Major Jackson Spencer (Miniseries) - Killed in Action
Captain Lee Adama (Miniseries to "The Captain's Hand") - Promoted to CO of Pegasus
Captain George Birch ("Home, Part I" to "Home, Part II") - Temporary replacement for Captain Adama
Captain Kara Thrace ("The Captain's Hand" to "Lay Down Your Burdens, Part II") - Relocates to New Caprica
Captain Louanne Katraine ("Lay Down Your Burdens, Part II" to "Collaborators") - Demoted when Major Adama resumes post. Posthumous and symbolic promotion ("The Passage")
Major Lee Adama ("Torn" to "The Son Also Rises") - Re-assigned as Head of Security for Romo Lampkin
Captain Karl Agathon ("The Son Also Rises" to present)

Chief Medical Officer

Major Cottle (Miniseries to present, with the exception of his relocation to New Caprica)
Unknown ("Lay Down Your Burdens, Part II" to "Exodus, Part II")

Chief of the Deck

Chief Petty Officer Galen Tyrol (Miniseries to "Pegasus") - Replaced by Pegasus's Deck Chief
Chief Petty Officer Peter Laird ("Pegasus" to "Resurrection Ship, Part II") - Laird reassigned to Pegasus
Chief Petty Officer Galen Tyrol ("Epiphanies" to "Lay Down Your Burdens, Part II") - Relocates to New Caprica
Unknown ("Lay Down Your Burdens, Part II" to "Exodus, Part II") - Tyrol resumes post
Chief Petty Officer Galen Tyrol ("Collaborators" to present)

Master-at-Arms

Sergeant Hadrian (Presumably "Miniseries" to present, but last mentioned in "Valley of Darkness")

Landing Signal Officer

Captain Aaron Kelly ("Miniseries" to "Exodus, Part I") - Re-assigned as Tactical Officer
Unknown ("Exodus, Part I" to "Exodus, Part II") - Felix Gaeta resumes post as Tactical Officer
Captain Aaron Kelly ("Collaborators" to present)

Senior Marine Commander

Lieutenant Terry Burrell (unknown, seen only in "Sacrifice")
Gunnery Sergeant Erin Mathias ("Exodus, Part I" or earlier to present)

Chain of Command

Presently, the first in command aboard Galactica is Admiral Adama, and the second in command is Colonel Tigh. Beyond that the hierarchy is unclear. Major Lee Adama is the next highest ranking officer (Major Cottle is a staff officer and outside of the chain of command). However, in past episodes both Captain Kelly and Captain Agathon have have served as seconds-in-command. While Lee Adama is on parole in "Scattered", and might have been passed over because of that, it is also possible that the CAG is not in line for the command of a battlestar. Given Captain Kelly's detention in "The Son Also Rises" he is presumably no longer a candidate.